Some of our users are currently experiencing problems when browsing. On
random sites images fail to appear and are replaced with a forbidden error.
This seem to occur when the images are located on a different URL / site.
This problem seems to be intermittent and can be fine for days then
regulary appear for a day after that. If users do encounter the problem, a
refrsh of the broswer often brings the images up as they should be.

Any suggestions or ideas as to what might be causing the problem would be
much appreciated.